visudo
edit the sudoers file
see also :
vi - sudo - vipw
Synopsis
visudo
[-chqsV]
[-f sudoers]
add an example, a script, a trick and tips
examples
source
echo "a /etc/sudoers
(sudo visudo) si fuera necesario"
confirm "Ejecutar sudo visudo
ahora" && sudo visudo
description
visudo edits the
sudoers file in a safe fashion, analogous to vipw(8).
visudo locks the sudoers file against multiple
simultaneous edits, provides basic sanity checks, and checks
for parse errors. If the sudoers file is currently
being edited you will receive a message to try again
later.
There is a
hard-coded list of one or more editors that visudo
will use set at compile-time that may be overridden via the
editor sudoers Default variable. This list defaults
to /usr/local/bin/vi. Normally, visudo does not honor
the VISUAL or EDITOR environment variables unless they
contain an editor in the aforementioned editors list.
However, if visudo is configured with the
--with-env-editor option or the env_editor Default
variable is set in sudoers, visudo will use
any the editor defines by VISUAL or EDITOR. Note that this
can be a security hole since it allows the user to execute
any program they wish simply by setting VISUAL or
EDITOR.
visudo
parses the sudoers file after the edit and will not
save the changes if there is a syntax error. Upon finding an
error, visudo will print a message stating the line
number(s) where the error occurred and the user will receive
the ’’What now?’’ prompt. At this
point the user may enter ’e’ to re-edit the
sudoers file, ’x’ to exit without saving
the changes, or ’Q’ to quit and save changes.
The ’Q’ option should be used with extreme care
because if visudo believes there to be a parse error,
so will sudo and no one will be able to sudo
again until the error is fixed. If ’e’ is typed
to edit the sudoers file after a parse error has been
detected, the cursor will be placed on the line where the
error occurred (if the editor supports this feature).
The options are
as follows:
-c
Enable
check-only mode. The existing sudoers file
will be checked for syntax errors, owner and mode. A message
will be printed to the standard output describing the status
of sudoers unless the -q option was
specified. If the check completes successfully,
visudo will exit with a value of 0. If an error is
encountered, visudo will exit with a value of 1.
-f
sudoers
Specify and
alternate sudoers file location. With this option
visudo will edit (or check) the sudoers file
of your choice, instead of the default, /etc/sudoers.
The lock file used is the specified sudoers file with
’’.tmp’’ appended to it. In
check-only mode only, the argument to -f
may be ’-’, indicating that sudoers will
be read from the standard input.
-h
The
-h (help) option causes visudo to
print a short help message to the standard output and
exit.
-q
Enable
quiet mode. In this mode details about syntax errors
are not printed. This option is only useful when combined
with the -c option.
-s
Enable
strict checking of the sudoers file. If an
alias is used before it is defined, visudo will
consider this a parse error. Note that it is not possible to
differentiate between an alias and a host name or user name
that consists solely of uppercase letters, digits, and the
underscore (’_’) character.
-V
The
-V (version) option causes visudo
to print its version number and exit.
caveats
There is no easy way to prevent a user from gaining a root shell
if the editor used by visudo allows shell escapes.
disclaimer
visudo is provided ’’AS IS’’ and any express or implied
warranties, including, but not limited to, the implied warranties
of merchantability and fitness for a particular purpose are
disclaimed. See the LICENSE file distributed with sudo or
http://www.sudo.ws/sudo/license.html for complete details.
Sudo 1.8.6p3 July 12, 2012 Sudo 1.8.6p3
environment
The following environment variables may be consulted depending on
the value of the editor and env_editor sudoers
settings:
VISUAL
Invoked by visudo as the editor to use
EDITOR
Used by visudo if VISUAL is not set
support
Limited free support is available via the sudo-users mailing
list, see http://www.sudo.ws/mailman/listinfo/sudo-users to
subscribe or search the archives.
bugs
If you feel you have found a bug
in visudo, please submit a bug report at
http://www.sudo.ws/sudo/bugs/
see also
/etc/
sudo ers
List of who can
run what
/etc/sudoers.tmp
Lock file for
vi sudo
sudoers file busy, try again later.
Someone else is currently
editing the sudoers file.
/etc/sudoers.tmp: Permission
denied
You didn’t run
visudo as root.
Can’t find you in the
passwd database
Your user ID does not appear in
the system passwd file.
Warning:
{User,Runas,Host,Cmnd}_Alias referenced but not defined
Either you are trying to use an
undeclared {User,Runas,Host,Cmnd}_Alias or you have a user
or host name listed that consists solely of uppercase
letters, digits, and the underscore (’_’)
character. In the latter case, you can ignore the warnings
(
sudo will not complain ). In -s
(strict) mode these are errors, not warnings.
Warning: unused
{User,Runas,Host,Cmnd}_Alias
The specified
{User,Runas,Host,Cmnd}_Alias was defined but never used. You
may wish to comment out or remove the unused alias. In
-s (strict) mode this is an error, not a
warning.
Warning: cycle in
{User,Runas,Host,Cmnd}_Alias
The specified
{User,Runas,Host,Cmnd}_Alias includes a reference to itself,
either directly or through an alias it includes. This is
only a warning by default as sudo will ignore cycles
when parsing the sudoers file.
vi, sudoers, sudo,
vipw
authors
Many people have worked on
sudo over the years; this version consists of code
written primarily by:
Todd C.
Miller
See the
CONTRIBUTORS file in the sudo distribution
(http://www.sudo.ws/sudo/contributors.html) for an
exhaustive list of people who have contributed to
sudo.